WASHINGTON - The United States "deeply regrets" over India's expulsion of an American diplomat amid an ongoing diplomatic row, the State Department said on Friday.

"I can confirm that a US official accredited to Mission India will be leaving post at the request of the government of India," spokeswoman Jennifer Psaki told reporters at a daily news briefing.

"We deeply regret that the India government felt it was necessary to expel one of our diplomatic personnel," she said. " This has clearly been a challenging time in the US-India relationship."

The tit-for-tat move came hours after Devyani Khobragade, the Indian diplomat at the heart of the diplomatic row festering and straining bilateral ties over the past month, was indicted on Thursday in a New York court on charges of visa fraud and asked to leave the United States immediately.

"We expect, and hope that this will now come to closure, and the Indians will now take significant steps with us to improve our relationship, and return it to a more constructive place," Psaki said.

India has been demanding an apology and a drop of charges against Khobragade, the country's former deputy consul general in New York arrested on December 12 when she was dropping her daughter off at school, over visa fraud charges relating to her mistreatment of her Indian housekeeper.

The 39-year-old diplomat was reportedly handcuffed, strip- searched, subjected to DNA swabbing and confined with drug addicts until her release on a 250,000-dollars bond.

India has taken a number of retaliatory measures, including removing the traffic barricades outside the US embassy in New Delhi, withdrawing identity cards that entitle consular officers to diplomatic immunity and airport passes for diplomats and their families, stopping import clearances for the US embassy, and most recently, ordering a shutdown of "commercial activities" at a recreational facility at the embassy by January 16.

The State Department accepted an Indian request to accredit Khobragade to its UN mission on Wednesday, but demanded a waiver of her diplomatic immunity for the charges against her to move forward.

"It was denied, and our policy, as a government, is to then ask for that individual to depart when there are serious charges involved," Psaki said.

Khobragade, who returned to New Delhi on Friday, is not permitted to return to the United States, "except to submit to the jurisdiction of the court," Psaki said.

"Her name would be placed in visa and immigration lookout systems to prevent the routine issuance of any future visa," the spokeswoman added.

US Secretary of State John Kerry expressed "regret" over the diplomatic row last month, but did not acknowledge any wrongdoing.

US Energy Secretary Ernest Moniz has delayed a trip to India originally scheduled for next week amid the uproar.